Phosphorus-31 NMR data for one-coordinate phosphorus compounds are extremely scarce in the literature. Recently, the first terminal phosphido (P3-) complexes containing a phosphorus-metal triple bond were successfully synthezied (1). Since these novel complexes exhibit unusual 31P chemical shieldings in solution, we set out to investigate the complete 31P chemical shielding tensor by solid-state 31P NMR. We have characterized the 31P chemical shielding tensor for a series of terminal phosphido complexes, Mo(P)[N(tBu)Ar3 (Ar=C6H5, 3,5-C6H3Me2) and M(P)(NN3) (NN3 = [Me3SiNCH2CH2)3N]3-, M = Mo, W) (2). It was found that all terminal phosphido complexes have 31P chemical shift anisotropy (CSA) on the order of 2000 ppm, which are the largest 31P CSA's in the literature. The unusually large 31P chemical shifts observed in solution are due to a significant paramagnetic shielding contribution along directions perpendicular to the phosphorus-metal triple bond. This paramagnetic shielding is interpreted as primarily due to a field-induced mixing between bonding sigma(M-P) and antibonding pi(M-P) molecular orbitals. Observation of such a large paramagnetic shielding contribution indicates a small energy gap between (M-P) and (M-P) MO's in this new type of complexes. Further experimental and theoretical studies about the nature of phosphorus-metal triple bonding are underway. (1) C.E. Laplaza, W.M. Davis, C.C. Cummins, Angew. Chem. Int. Ed. Engl. 34, 2044 (1995); N.C. Zanetti, R.R. Schrock, W.M. Davis, Angew. Chem. Int. Ed. Engl. 34, 2044 (1995).